He doesn't get out much, spending about 16 hours a day at the computer. When he ventures from his Center City apartment, it's unlikely that he's made: he prefers to keep his picture out of the papers. It was only a year ago, during the Democratic National Convention, that he let out his secret to his friends and parents.

To more than 120,000 visitors a day, he is known as Atrios, the acid-tongued, left-brained blogger who runs the site called Eschaton, named after a complicated war game at a private tennis academy in David Foster Wallace's book Infinite Jest.

Atrios is no joke. By some measures - such as Blogstreet - he is the most influential writer in the 13 million-blog business.

We lunched with the dark prince this week at Nodding Head Brewery. In person, Black, 33, is confident and careful, probing each question for landmines, coming across more like the "recovering economist" he says he is than the firebrand who manages to work his readers into a regular froth by providing a rough-and-tumble forum for their thoughts - a sort of Australian-Rules Liberalism.

He is tall - over six feet - with longish hair and a freshly laundered shirt and slacks. In person and in print he doesn't waste words. After two beers, his tongue was no looser. If I didn't fear Patrick Fitzgerald, I'd say Black would make a good spy.

Before outing himself, Atrios's identity was a mystery. He was thought by many to be a suburban Philadelphia educator - gym teacher, many mused. After some posts on Salon's Table Talk, he introduced his new blog to the world in April 2002 with the question: "Is this thing on?" He wondered how long before literally dozens of people were reading him on an almost monthly basis.

His readership rocketed into the hundreds of thousands that December when he hammered Trent Lott after the Senate Majority Leader said of fellow senator and southerner Strom Thurmond, "if the rest of our country had followed our lead, we wouldn't have had all these problems over all these years, either." Thurmond was a former segregationist, remember.

Where the Washington press corps ignored Lott's birthday-party remarks, Atrios and fellow blogger Joshua Micah Marshall feasted. Atrios dug up a campaign pamphlet from 1948 in which Thurmond warned that the election of Harry Truman would mean "anti-lynching and anti-segregation proposals will become the law of the land and our way of life in the South will be gone forever." In Blogging America, the author Barbara O'Brien says this portrayed Lott, essentially, as endorsing separating of the races. Five days later, the New York Times picked up the story. Lott resigned.

Black was actually teaching economics at Bryn Mawr College at the time. He'd come to Philadelphia shortly beforehand, when his wife took a job as a professor. He'd grown up here, moving near Collegeville in middle school - it was his 7th or 8th address already, thanks to his father's computer-industry job.

Today Black lives with his wife in a Center City apartment where he spends most of his time online, reading and writing a blog that gets so many hundreds of comments a day that a friend created a program for him that would spit out "open threads" so people could talk among themselves every two hours.

It is more than full time work - waking up too early, and pouring through a combination of what he wants to know and needs to know. His reading usually begins with the New York Times and Washington Post, then the Los Angeles Times and West Coast bloggers, to pick up what he missed after going to bed too late.

Eschaton is known for short, sharp posts that collect and contextualize the news and opinion of the day that interests him, delivered with commentaries that drip with sarcasm. A sampling from Thursday:

Of GOP Senators Kit Bond and Kay Hutchison's televised press conference supporting Karl Rove: "Well, that was a rather disgusting performance on CNN." Of Rush Limbaugh's criticism of GOP leaders for renouncing its civil-rights-era strategies, "Over the top, even for him." And headline on a story about a Sen. Rick Santorum aide who is gay: "Woof." A reference, we gather, to the Republican senator's curious comments about man-on-dog relations.

Black makes a living at this. He takes ads and since January has grossed about $5,000 a month, he says. He has few costs. He also writes for Media Matters for America, a progressive non-profit that counters conservative influence on the news. It's named him a senior fellow. This has led some critics, like Charles Johnson of Little Green Footballs, to say Black works for George Soros, the Bush-hating Democratic Party patron.

It would be a compliment if it were true, says Black. Last time he checked, Soros hadn't given any money to Media Matters, although the claim persists online and in conversation with conservatives.

After a couple years making hay with the news, Black has found himself in the headlines lately. He went to Washington earlier this month to testify before the Federal Election Commission, which is considering whether to regulate bloggers' political activities. He traveled with his lawyer, Adam Bonin, a Philadelphian who also blogs. (earlier Blinq post here.)

Black says he raised a half million dollars for the Kerry campaign as well as other Democratic candidates. Some good-government types fear that bloggers could pose a loophole in election finance laws that would allow corporations to funnel unlimited funds into campaigns. Black and Bonin counter that sunshine and the market should cure the problem - voluntary disclosure of funding by bloggers and real-time publication of campaign contributions.

As Black told the commissioners: "I am troubled by the fact that participants in this emerging medium, which allows anyone the opportunity to participate in the national discourse at a minimum cost would face stricter regulation and stronger scrutiny along with the potential for ruinous legal expense than would participants in media outlets owned by corporations such as Time Warner, General Electric and Disney."

I asked him why he thinks his site is so popular. His face wrinkled. He answered it this way.

"Politics and religion are very sensitive subjects. People want to go where there are like-minded people. They don't always want to debate. Blogs do kind of provide a virtual community that allows people to participate in a shared narrative that is absent elsewhere."